Abstract: A tissue culture system for production of infectious hepatitis C virus is described. In particular, the invention provides recombinant monocistronic and bicistronic genomic constructs for production of virus, including constructs for production of wild-type HCV type 2a strain JFH1 and constructs for production of chimeric viruses comprising HCV proteins from strain JFH1 and a second HCV isolate. Constructs of the invention also include a reporter gene to facilitate measurement of RNA replication and viral infectivity in cultures. The cell culture system may also include various factors that improve viral replication or infectivity. In addition, a neutralization assay using HCV grown in cell culture is described.

Abstract: A method and system is provided for enhancing an audio signal based on spectral subtraction. The noise power spectrum for each frame of an audio signal is dynamically estimated based on a plurality of signal power spectrum values computed from a corresponding plurality of adjacent frames. An over-subtraction factor is then dynamically computed for each frame based on the noise power spectrum estimated for the frame. The signal power spectrum of the audio signal at each frame is then reduced in accordance with the over-subtraction factor computed for the corresponding frame.

Abstract: A method and system is provided for enhancing an audio signal based on spectral subtraction. The noise power spectrum for each frame of an audio signal is dynamically estimated based on a plurality of signal power spectrum values computed from a corresponding plurality of adjacent frames. An over-subtraction factor is then dynamically computed for each frame based on the noise power spectrum estimated for the frame. The signal power spectrum of the audio signal at each frame is then reduced in accordance with the over-subtraction factor computed for the corresponding frame.